Pull the cover off a washing machine, follow the air line on a small compressor or look under the fuel tank of a lawn tractor, and you’ll probably spot a thin metal ring with two little humps sticking up from it. So what is a double ear clamp? Here’s the short answer before we go into detail:
A double ear clamp is a narrow steel band formed into a ring, with two raised loops (“ears”) pressed into it. Squeezing each ear shut with pincers permanently shortens the band, so the ring tightens around a hose and holds it on a fitting. It can’t be loosened; it’s cut off to remove.
That’s the dictionary answer to what is a double ear clamp. Following one clamp through its life explains it better: how it’s made at the factory, how it sits in a box, what happens to the metal when it’s crimped, how it behaves for years on a hose, and how it finally comes off. Along the way we’ll cover the different types, where you’ll come across them, and how to tell a two ear clamp apart from the other crimped parts that look like it.
A quick note before we start: OneTouch Exim doesn’t stock or sell ear clamps. Our range is screw-tightened and V-band clamps. Buyers often ask us about crimped rings when they’re deciding whether a screw clamp would suit them better, so this page simply explains the part. Our own suggestions come at the end.
Stage one: how a double ear clamp is made
Every double ear clamp starts as a coil of flat steel strip. Methods vary by maker, but the basic steps explain a lot about how the finished part behaves.
Slitting the strip to band width
Wide coil is slit into narrow ribbons, each one the width of the finished band. These ribbons are slim: a few millimetres on the smallest sizes and around a centimetre on larger ones. Narrow is deliberate: closing force over a small contact area means high pressure on the hose.
Pressing the ears
Next the strip goes through a press tool that forms the two ears. Each ear is an upside-down U standing up from the band, with two legs and a rounded top. The amount of strip that goes into each ear is fixed in the tool. That length sets the clamp’s future take-up, because closing an ear takes exactly that length out of the ring. Many designs also press a small dimple or rib into each ear. The dimple adds stiffness and lets the shut ear flex very slightly.
Cutting, rolling and joining
The formed strip is cut to length and rolled into a ring. Where the two ends meet they overlap, and they’re fixed together by a spot weld or a pressed interlock, depending on the design. This overlap matters later. It leaves a small ledge inside the ring, one band-thickness high, where the ends lap. Firm hose barely notices it. Very thin or very hard tubing can.
Finishing the edges and surface
Slit steel has sharp, slightly burred edges that could score a hose. Good manufacturers deburr or round the band edges so the clamp presses the hose without cutting it. Oetiker’s catalogue for its 1-ear and 2-ear clamp ranges lists deburred edges as a standard feature. The finished rings are then plated if needed, and sorted by size.
The two materials you’ll meet
- Low-carbon steel with zinc plating. Shiny silver or slightly yellow, depending on the passivation. It’s the low-cost choice for dry, sheltered jobs.
- Austenitic stainless steel. Usually a 304-family grade, with a duller, even grey finish. Oetiker’s catalogue lists its stainless two-ear series in a low-carbon 304 variant and rates it far higher than the zinc-plated version in corrosion testing.
You can usually tell them apart with a magnet. Zinc-plated carbon steel snaps onto it, while annealed 304 stainless barely reacts. Our article on magnetic vs non-magnetic stainless steel explains why cold-worked stainless can still pull weakly, so treat the magnet as a hint rather than proof.
Anatomy at a glance
| Part of the clamp | What it looks like | What it does |
|---|---|---|
| Band | Flat steel ribbon forming the ring | Squeezes the hose onto its barb or spigot |
| Ear (×2) | Raised U-shaped loop, about as tall as it is wide | Holds the spare band length that tightens the ring when the ear is closed |
| Ear legs | The two sides of each loop where it joins the band | Where the pincer jaws grip; pulling them together closes the ear |
| Dimple or rib | Small pressed dent in the top of the ear (on some designs) | Adds stiffness and a touch of spring |
| Overlap joint | The spot where the band ends meet, welded or interlocked | Closes the ring; leaves a small step on the inside |
| Band edges | The two long sides of the ribbon, ideally rounded | Grip the hose without cutting it if properly deburred |
Stage two: in the box, waiting to be used
A new double ear clamp is slightly larger than its intended hose, so it can be pushed over the end without a fight. That open diameter is one end of its working range. The other end is the closed diameter, the size the ring shrinks to after both loops are crimped shut. The usable window sits between those two figures, and it’s small.
Storage has two small cautions. Zinc-plated clamps in a damp shed can grow white corrosion spots before they’re fitted. And clamps tipped loose into a bin get knocked until some ears are half-flattened, which wastes take-up before the clamp is ever used. Keep them bagged and labelled by size and material.
Stage three: how a double ear clamp works when crimped
This is the real answer to how does a double ear clamp work. Nothing turns, threads or ratchets. The clamp tightens because metal is bent permanently out of shape.
Plastic deformation does the work
Steel has two ways of responding to force. Below a certain stress it bends elastically and springs back once the force is removed. Above that stress, called the yield point, it bends plastically and stays bent. Ear pincers grip the two legs of an ear near the band and pull them together. The bends at the bottom of the legs and across the top of the loop are pushed past yield, so the ear folds into a closed, flattened shape and stays that way when the tool lets go.
Bringing the legs together takes the strip that was stored in the loop out of the ring’s circumference. The ring gets shorter, which means it gets smaller in diameter. Once it’s pressing on the hose, any further closing turns into tension in the band. The tension pushes the rubber inward onto the barb or spigot. That compression is what seals the joint and stops the hose slipping off.
Why two ears instead of one
Each ear can remove only as much circumference as it contains. Diameter equals circumference divided by pi (about 3.14), so the change in diameter is roughly a third of the length the ear removes. Here’s a made-up example to show the scale. Suppose each ear holds about 7 mm of strip. Closing one ear could shorten the ring by about 7 mm and reduce the diameter by a bit over 2 mm. Closing both ears doubles that, to about 4.5 mm. In practice the figure is a bit lower, because ears seldom close to a zero gap.
That bigger reduction is why a two ear design exists. A single size covers a wider spread of hose diameters, which is useful when hose from different batches isn’t quite the same thickness. Oetiker’s catalogue mentions that a further crimping step may be required for proper closure. Wikipedia’s hose clamp article adds that an ear clamp should be sized so its ears end up almost fully closed when fitted.
Compare that with a screw clamp. Each OneTouch range below covers about 9 mm of diameter or more, roughly twice what a two ear clamp can take up. The figures show the difference between a fixed crimp and an adjustable band:
| Clamp | Listed range | Span of diameters covered | How the span is used |
|---|---|---|---|
| Illustrative two ear clamp (two 7 mm ears) | Open to closed, a few mm apart | Up to about 4.5 mm in theory | Used once; set when the ears close |
| OTE-4SC004M mini worm clamp | 0.25 to 0.63 in | 0.38 in (about 9.7 mm) | Tighten, loosen and reuse with a screw |
| OTE-4SC006M mini worm clamp | 0.44 to 0.78 in | 0.34 in (about 8.6 mm) | Tighten, loosen and reuse with a screw |
| OTE-4SCH004 lined clamp | 0.25 to 0.62 in | 0.37 in (about 9.4 mm) | Adjustable, with a smooth liner over the band slots |
The ear as a small spring
Once it’s closed, an ear isn’t completely rigid. The folded loop, especially one with a dimple, acts as a very stiff, very short spring. If the hose grows slightly when it warms up, the ear gives a little. When it shrinks again, the ear takes back some of that movement, so the band keeps contact. Oetiker describes its two-ear clamps as having elasticity to cope with size changes, and Wikipedia credits ear dimples with a similar spring effect.
The key word is small. The ear can make up for fractions of a millimetre. It can’t follow the large heat cycles of an engine coolant hose the way a spring-washer clamp can. Why that matters on hot joints is covered in our constant tension vs standard clamp explainer.
What the closed ear tells you
Because the deformation is permanent and easy to see, a closed ear is its own inspection record. A correctly crimped ear has its legs meeting at the base, not merely a squashed crown. An inspector can check that at a glance, and a pried-open ear looks kinked, so tampering shows too. That visible proof is a big reason assembly lines specify crimps.
Stage four: what is a double ear clamp doing in service?
Once it’s on, a properly closed double ear clamp needs nothing. There’s no screw to vibrate loose and no housing to catch on wiring, and the ears stand only a few millimetres off the hose. On firm hose over a ridged barb, the ridges resist pull-off and the band keeps the rubber seated over them.
Over the years, the things that wear a double ear clamp out are the same things that wear out any clamp:
- Corrosion. Zinc plating scratched by the pincer jaws rusts first at the ears. On a wet or outdoor joint, a zinc clamp can turn into a brown ring within a few seasons.
- Hose relaxation. Rubber slowly takes a set under constant pressure. As the wall thins under the band, clamping force falls. The ear’s small spring delays this but doesn’t stop it.
- Hose ageing. The clamp often outlasts the hose. Cracked, hardened tubing under a perfectly good clamp is a common find on older appliances and small engines.
Double ear hose clamp types
Catalogues group two ear clamps in a few overlapping ways. Knowing them helps you read a supplier listing or describe a part you’ve pulled off a machine.
By material
This is the main split: zinc-plated steel for dry interiors, and 304-family stainless anywhere water, weather, food or cleaning chemicals are involved. Where salt or pool water is involved, read about how 304 and 316 stainless differ.
By band width and thickness
Small diameters use the narrowest, thinnest bands, and band width and thickness both step up with diameter. Thicker bands hold more force but need more force to close. On larger sizes that’s often beyond what hand pincers can manage. The Oetiker catalogue mentioned above lists higher maximum closing forces for its larger two-ear sizes and pairs them with powered closing tools.
With or without a protective insert
Some ear clamp lines are sold with a thin inner strip that bridges the opening beneath the ear and the overlap ledge, to protect soft hose. In the Oetiker catalogue we checked, the insert option is listed on a single-ear product group, not the two-ear groups. If you need an insert, check each maker’s range rather than assuming one exists for two ear designs. For very soft or thin tubing, most engineers go to a stepless single-ear clamp instead.
By name: “mechanical”, “pinch”, “Oetiker-style”
You’ll see the same part called a two ear clamp, double ear hose clamp, pinch clamp, crimp clamp, mechanical clamp or simply an Oetiker clamp. The last name comes from Oetiker, the Swiss company founded by Hans Oetiker in 1942. According to the company’s own 75th anniversary history, it patented the first ear clamp in 1951. The brand became so closely linked with the product that “Oetiker clamp” is now used for any ear clamp, whoever made it, much as people say “Jubilee clip” for any worm drive clamp in the UK. Strictly speaking, only Oetiker makes Oetiker clamps. Many other makers produce two ear designs to similar dimensions.
Reusable versions?
There aren’t any. A reusable double ear clamp would contradict the way the part works, because the tightening comes from permanent deformation. “Reusable ear clamp” listings usually turn out to be ratchet bands or small screw clamps.
Double ear clamp uses: where you’ll meet them
Double ear clamp uses have a lot in common: small diameters, firm hose on a barb, modest pressure and joints that seldom need opening. Here’s where you’re most likely to find them:
- Air hose. Shop-air pigtails, compressor accessory lines and pneumatic tool whips, where reinforced PVC or rubber hose is pushed onto brass barbs.
- Garden and irrigation barbs. Poly drip-line fittings, pump outlets and hose-tail adaptors, usually in stainless for outdoor life. Our garden hose and irrigation clamp guide covers the screw clamp side.
- Fuel return lines on small engines. Mowers, generators and small outboards often use a crimp on the low-pressure return and vent hoses.
- Washing machines and appliances. Inlet, drain and internal water hoses, where the low profile and tamper evidence suit high-volume assembly.
- Beverage and water lines. Drink dispensers, water coolers and coffee machines, usually in stainless on food-grade tubing.
- Agricultural sprayers. Boom-section feed lines, nozzle body hoses and tank fittings on knapsack and trailed sprayers.
You won’t find them on big-bore truck hoses, turbo couplers or hot coolant joints; those need wider bands, more adjustment or spring take-up.
How to tell a double ear from look-alike crimped parts
Knowing what is a double ear clamp also means knowing what it isn’t. Here’s how to identify an unfamiliar crimped ring you’ve pulled off a machine.
Count the ears
Two raised loops, usually close together on the same side of the ring, mean a double ear clamp. One loop means a single ear clamp.
Look inside the ring
Run a fingernail around the inside. If it catches on a ledge at the lap joint, it’s a standard open-overlap clamp. If the inside is completely smooth and there’s a tongue tucked into a pressed channel, it’s a stepless single-ear design. Stepless clamps are made for hard plastic tube and CV boots, and choosing a stepless ear clamp explains why the smooth bore matters.
Check whether there are ears at all
A plain copper or stainless ring that’s been squeezed evenly all the way round, with no ears, is a crimp ring. PEX plumbing uses these, closed with a matching jaw tool. A stainless ring with a single flat tab, not a loop, is usually a PEX cinch clamp. Neither is interchangeable with a general-purpose ear clamp.
Is it a sleeve rather than a band?
A thick, cup-shaped metal sleeve swaged onto the end of a hydraulic or air brake hose is a ferrule. It’s pressed by a crimping machine as part of a factory-made hose assembly and can’t be fitted in the field. If you find one, replace the whole hose assembly. Don’t try to clamp it.
Two loops of wire?
Two parallel loops of round wire, pulled together by a screw and saddle, are a double wire clamp, not a double ear clamp. The names sound alike, but double wire clamps are screw-tightened and can be reused.
Take the right measurement
To order a replacement, the useful figure is the hose OD where the clamp sat, measured with the hose still on its fitting. The size printed on an old clamp is less use than you’d think, because labels vary from maker to maker. For converting between catalogue units, keep our mm and inch clamp size chart handy.
Stage five: removing a double ear clamp safely
Every crimped clamp ends up being cut off. Done carelessly, that’s where hoses and fittings get damaged. The aim is to cut the clamp, not the hose underneath it.
- Use end cutters (end nippers). Their jaws meet at the front, so you can grip a closed ear from above. Side cutters work in a pinch but tend to slip onto the band.
- Bite the crown of an ear, not the band. The ear stands clear of the hose, so snipping across the folded crown is the one place where the blades don’t press into rubber. One firm squeeze is usually enough to snap the ear.
- Peel the band open. Once the ear is cut, the tension is released. Lift one cut end with a small flat screwdriver and unwrap the ring. On a stainless clamp the ends are sharp, so wear gloves.
- Don’t slit the hose to get it off. If the hose is stuck on the barb, twist it gently or warm it. Wikipedia’s hose clamp entry also warns against slitting stuck hoses, because a knife scratches the fitting and creates a leak path for the next hose.
- Look at what was underneath. A clean, even ring pressed into the hose means the clamp was doing its job. A deep cut means it was too small or over-closed. A rusted band means the next one should be stainless.
Bin the old clamp; its cut ear can’t tighten anything again.
Common misconceptions about two ear clamps
“The second ear is a spare”
It isn’t. The clamp is sized on the assumption that both ears close. Leave one standing and you’ve lost half the take-up, so on most hoses the band will be loose.
“Squeeze harder for a better seal”
Past full closure, extra force only crushes the fold and may split it. If the clamp still turns on the hose after both ears are shut, it’s the wrong size. More grip won’t fix that.
“Any pliers will do”
Ordinary pliers squash the crown without drawing the legs together, so the clamp looks closed but barely tightens. Ear pincers are cheap and they’re the right tool.
“Two ears are always stronger than one”
Two ears give more adjustment, not more holding force. Clamping force depends on band size, material and how well the ears are closed. A good single-ear clamp on the right hose holds just as well. For the one-loop option, see how to choose a single ear clamp.
“Oetiker is a type of clamp”
It’s a company name that became a common word. When a parts list says “Oetiker clamp”, check whether it means that brand’s part number or any ear clamp of that size.
Your next step
Now you know what is a double ear clamp, the next question is which one to buy. Sizing, band width, material and tooling are all covered in our double ear clamp buying guide, so we won’t repeat them here.
If the joint will need opening at service, or the hose size is uncertain, a small screw clamp is often the more practical choice. The OTE-4SC004M mini hose clamp (0.25–0.63 in) and the OTE-4SC006M (0.44–0.78 in) cover the barb sizes where two ear clamps are most common. For soft hose, the OTE-4SCH004 lined clamp puts a smooth liner between the band slots and the hose. Our mini hose clamp guide explains housing size and screw access. Holding only an OEM number? Send it through our clamp cross-reference and we’ll tell you honestly whether a screw clamp suits that joint.
Double ear clamp FAQs for beginners
What is a double ear clamp called in catalogues, and why “ear”?
Catalogues list it as a double ear, two ear, 2-ear or pinch clamp. The ear clamp meaning comes from shape: before closing, each raised loop sticks up from the band like a small ear. One loop makes a single ear clamp and two make a double ear clamp. The loop itself is always just called “the ear”.
Is every two ear clamp an Oetiker clamp?
No. Oetiker is a Swiss company that patented an early ear clamp design, and its name is now used loosely for the whole category. Many other makers produce two ear clamps in zinc-plated and stainless steel. If a parts list asks for an Oetiker part number, use that exact part or a confirmed equivalent with the same range, band width and material.
Do both ears have to be closed?
Yes. The clamp’s range assumes both ears are closed, and each one provides part of the take-up. Close one and leave the other open, and the band will usually stay loose on the hose. Close the ears one after the other, gripping at the base of each, until the legs meet. Neither ear is meant to be kept back for adjustment later.
What’s the easiest way to cut off a double ear clamp?
Use end cutters and bite across the top of one closed ear, where it stands clear of the hose. That releases the band tension, and you can then peel the ring away with a small screwdriver. Don’t cut across the flat band, because the blades will press into the hose. Don’t slit the hose either, as a knife can scratch the barb and cause leaks later.
How long does a double ear clamp last?
A properly closed stainless clamp in a dry or mildly damp place can outlast the hose it holds. A zinc-plated clamp lasts well indoors but can rust quickly outdoors or wherever its plating has been scratched. Most failures come from hose ageing, corrosion or the wrong size, not from the ears coming open. Check old hoses for cracking near the band.
Can a double ear clamp hold hard plastic tubing?
It can, but it isn’t the best choice. Hard nylon or polyethylene tube can’t flow into the lap-joint ledge or the openings beneath the ears, so tiny leak paths can remain. Over-closing can also crack hard tube. For rigid thermoplastic lines, manufacturers usually specify stepless single-ear clamps closed with a force-controlled tool. Follow the equipment maker’s specification.
Prefer a clamp a mechanic can undo?
Swapping a factory crimp on a serviced joint? Tell us the installed hose OD, what the hose is made of, how hot it runs and any OEM numbers. Our team will match a OneTouch mini, lined or constant torque clamp and price anything from one piece to full export cartons, delivered worldwide. WhatsApp or call +91-7838759114.
Oetiker is named purely as a reference; OneTouch Exim is not connected with that company or any other ear clamp maker.